Objective To analyze the learning curve of unilateral biportal endoscopic lumbar interbody fusion (UBE-LIF). Methods Fifty-five patients with single-segment lumbar degenerative disease treated with UBE-LIF between December 2020 and February 2022 were selected as the research subjects. The patients were grouped according to the operation sequence, the first 27 cases were in the early group, and the last 28 cases were in the late group. There was no significant difference between the two groups in age, gender, disease type, and surgical segment distribution (P>0.05). The operation time, the amount of hemoglobin loss (the difference between 1 day before operation and 3 days after operation), the hospital stay after operation, and the incidence of perioperative complications were recorded; the learning curve of UBE-LIF was analyzed by log-curve regression analysis. Results All the operations were successfully completed without changing to other operations. The operation time, the amount of hemoglobin loss, and hospital stay in the early group were significantly more than those in the late group (P<0.05). Complications occurred in 2 cases (7.4%) in the early group, including 1 case of dural tear during operation and 1 case of epidural hematoma after operation, and 1 case (3.6%) with transient radiculitis in the late group. There was no significant difference in the incidence of complications between the two groups (P=0.518) . The log-curve regression analysis showed that the operation time decreased significantly with the increase of the number of patients (P<0.05). The operation time tended to be stable after the surgeon completed 17 cases. ConclusionFor single-level lumbar degenerative disease, the operation time of UBE-LIF can decrease gradually with the increase of the number of patients, and tend to be stable after 17 cases.